If they pass weight, the old floats should still be OK. It's never been said that all the old B floats were bad, but certainly enough were that they warranted a new model. I did have problems with the B floats, but I've been using the Rs for nearly two years now with no issue.
If you have already bitten the bullet and ordered new floats, you might as well put them in right away. Depending on how accessible your carbs are, changing out the floats is not at all difficult.
